#include <stdio.h>
void func(const char *file_name){
    int c = 'a';
    FILE *fptr = fopen(file_name,"w");
    if (fptr == NULL){
        /* Handle error */
    }
    while (c <= 'z'){
        if (putc(c++,fptr)==EOF){
            /* Handle error */
        }
    }
    if (fclose(fptr) == EOF){
        /* Handle error */
    }
}